[Systolic time intervals in essential hypertension. II. Variations produced by treatment with labetalol].

Characteristic changes in the systolic time intervals in Stage II (WHO Classification) hypertension have been demonstrated comprising an increase in the pre ejection period (PEP), a decrease in the left ventricular ejection time (LVET) both statistically significant, and an increase in the PEP/LVET ratio. We have studied the variations brought about by effective hypotensive therapy with an alpha and beta blocking agent (Labetalol) in 15 patients over a period of 90 days, with an average dosage of 420 mg/day in three divided doses. There was no significant variations in the PEP, but the LVET which had been reduced by 7.9% returned to within 2.8% of normal, with a reduction in the PEP/LVET ratio. The variations of these systolic indices (generally considered to be the most sensitive assessment of left ventricular function) seem to show that the hypotensive effect of labetalol is not related to a reduction in cardiac efficiency.